2026 Rankings

ZIP Codes with Most EPA Violations in California — 2026

Last updated: June 4, 2026

1,452 ZIP codes ranked by Violations #1: ZIP 93283 (Weldon, CA) — 48
Lead Violations Lowest Score Safest Flood Risk Energy Cost Radon PFAS Reliability EJ Index Homebuyer Risk CO & Gas Safest Gas Remediation Burden Unresolved Violations (by Utility) Water Equity (by Utility)

Out of 1,452 ZIP codes with data in California, these are the highest-ranked areas for violations. See also: National ZIP Codes with Most EPA Water Violations | All California Rankings

Statistic Value
ZIP codes ranked 1,452
Highest value 48
Median value 3
State California

Top 100 Worst ZIP Codes

Rank ZIP Code City State Violations Safety Score
1 93283 Weldon CA 48 55/100
2 95326 Hughson CA 36 70/100
3 92311 Barstow CA 31 45/100
4 92312 Barstow CA 31 39/100
5 93560 Rosamond CA 30 28/100
6 94561 Oakley CA 29 53/100
7 92069 San Marcos CA 28 66/100
8 92078 San Marcos CA 28 71/100
9 92079 San Marcos CA 28 69/100
10 92096 San Marcos CA 28 69/100
11 92626 Costa Mesa CA 28 52/100
12 92627 Costa Mesa CA 28 57/100
13 92628 Costa Mesa CA 28 55/100
14 93285 Wofford Heights CA 25 58/100
15 94972 Valley Ford CA 25 60/100
16 93240 Lake Isabella CA 24 59/100
17 93534 Lancaster CA 24 48/100
18 93535 Lancaster CA 24 43/100
19 93536 Lancaster CA 24 43/100
20 93539 Lancaster CA 24 36/100
21 93584 Lancaster CA 24 36/100
22 93586 Lancaster CA 24 36/100
23 93643 North Fork CA 24 50/100
24 92338 Ludlow CA 23 50/100
25 93247 Lindsay CA 22 28/100
26 93433 Grover Beach CA 22 58/100
27 93483 Grover Beach CA 22 50/100
28 93926 Gonzales CA 22 53/100
29 95012 Castroville CA 22 53/100
30 91354 Valencia CA 21 47/100
31 91355 Valencia CA 21 47/100
32 91385 Valencia CA 21 35/100
33 92327 Daggett CA 21 17/100
34 91963 Potrero CA 20 55/100
35 91990 Potrero CA 20 55/100
36 93244 Lemon Cove CA 20 41/100
37 90801 Long Beach CA 19 75/100
38 90802 Long Beach CA 19 75/100
39 90803 Long Beach CA 19 65/100
40 90804 Long Beach CA 19 70/100
41 90805 Long Beach CA 19 65/100
42 90806 Long Beach CA 19 70/100
43 90807 Long Beach CA 19 70/100
44 90808 Long Beach CA 19 70/100
45 90809 Long Beach CA 19 73/100
46 90810 Long Beach CA 19 70/100
47 90813 Long Beach CA 19 70/100
48 90814 Long Beach CA 19 70/100
49 90815 Long Beach CA 19 70/100
50 90822 Long Beach CA 19 73/100
51 90831 Long Beach CA 19 73/100
52 90832 Long Beach CA 19 73/100
53 90833 Long Beach CA 19 73/100
54 90834 Long Beach CA 19 73/100
55 90835 Long Beach CA 19 73/100
56 90840 Long Beach CA 19 73/100
57 90842 Long Beach CA 19 73/100
58 90844 Long Beach CA 19 73/100
59 90846 Long Beach CA 19 73/100
60 90847 Long Beach CA 19 73/100
61 90848 Long Beach CA 19 73/100
62 90853 Long Beach CA 19 73/100
63 90899 Long Beach CA 19 73/100
64 95950 Grimes CA 19 58/100
65 91316 Encino CA 18 23/100
66 91416 Encino CA 18 17/100
67 91426 Encino CA 18 17/100
68 91436 Encino CA 18 18/100
69 92065 Ramona CA 18 73/100
70 93501 Mojave CA 18 58/100
71 93502 Mojave CA 18 50/100
72 94556 Moraga CA 18 66/100
73 94570 Moraga CA 18 45/100
74 94575 Moraga CA 18 45/100
75 93245 Lemoore CA 17 70/100
76 93246 Lemoore CA 17 66/100
77 93532 Lake Hughes CA 17 53/100
78 95367 Riverbank CA 17 62/100
79 93620 Dos Palos CA 16 55/100
80 94582 San Ramon CA 16 50/100
81 94583 San Ramon CA 16 53/100
82 92301 Adelanto CA 15 79/100
83 93220 Edison CA 15 39/100
84 93614 Coarsegold CA 15 63/100
85 95559 Phillipsville CA 15 91/100
86 91931 Guatay CA 14 33/100
87 92539 Anza CA 14 58/100
88 92101 San Diego CA 13 35/100
89 92102 San Diego CA 13 60/100
90 92103 San Diego CA 13 60/100
91 92104 San Diego CA 13 65/100
92 92105 San Diego CA 13 60/100
93 92106 San Diego CA 13 60/100
94 92107 San Diego CA 13 60/100
95 92108 San Diego CA 13 55/100
96 92109 San Diego CA 13 55/100
97 92110 San Diego CA 13 60/100
98 92111 San Diego CA 13 65/100
99 92112 San Diego CA 13 60/100
100 92113 San Diego CA 13 55/100

Methodology

Violation counts include all types recorded in the EPA SDWIS database: Maximum Contaminant Level (MCL) violations, treatment technique violations, and monitoring/reporting violations. Both resolved and unresolved violations are counted. Higher counts may reflect longer system histories or larger service areas.

Data sources: EPA Safe Drinking Water Information System (SDWIS), FEMA National Flood Insurance Program, EPA radon zone maps, EIA electricity rates, and Consumer Confidence Reports. Last updated: 2026-06-04.

Frequently Asked Questions

What counts as an EPA water violation?

EPA violations include exceeding Maximum Contaminant Levels (MCLs), failing to treat water properly (treatment technique violations), and not testing or reporting on schedule (monitoring violations). Health-based violations are the most serious.

Does a high violation count mean the water is unsafe now?

Not necessarily. Many violations are historical or monitoring-related. However, a pattern of repeated violations indicates systemic issues with water system management or infrastructure.

Explore More Rankings

How this ranking is calculated, data sources, and limitations: Rankings Methodology →

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Disclaimer: Rankings are based on EPA, FEMA, and federal agency data. They reflect historical patterns and risk indicators, not necessarily current conditions. For the most current information, contact your local water utility or request a Consumer Confidence Report.

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